ML20116D007
| ML20116D007 | |
| Person / Time | |
|---|---|
| Site: | Waterford  |
| Issue date: | 07/17/1996 |
| From: | Sellman M ENTERGY OPERATIONS, INC. |
| To: | NRC OFFICE OF INFORMATION RESOURCES MANAGEMENT (IRM) |
| Shared Package | |
| ML20116D010 | List: |
| References | |
| W3F1-96-0004, W3F1-96-4, NUDOCS 9608010270 | |
| Download: ML20116D007 (8) | |
Text
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hENTERGY ET P"" " '"'
Killona, LA 700060751 Tel 504 739 6600 Mike Sellman
%ce Pres dent Ortf ahons W3F1-96-0004 A4.05 PR i
July 17,1996 U.S. Nuclear Regulatory Commission Attn: Document Control Desk l
Washington, D.C. 20555
Subject:
Waterford 3 SES Docket No. 50-382 License No. NPF-38 Technical Specification Change Request NPF-38-174 Gentlemen-i The attached description and safety analysis support a change to the Waterford 3 Technical Specifications (TS).
j The proposed change extends the surveillance interval for the Reactor Trip Breakers (RTBs) from monthly to quarterly and increases the allowed outage time for operation with an inoperabic RTB from one hour to two hours.
This request constitutes a lead-plant submittal, submitted by Waterford 3 on behalf of the Combustion Engineering Owners Group (CEOG). CE NPSD-951," Reactor Trip Circuit Breakers Surveillance Frequency Extension" was developed to support this proposed changed and will be provided for your review and approval under separate cover by the CEOG.
CEOG report CE NPSD-951 represents a follow-up to CEN-327, RPS ESFAS Extended Test Interval Evaluation, that justified extending the test interval for components in the RPS/PPS from monthly to quarterly. The Reactor Trip Breakers were not included in the CEN-327 study. CE NPSD-951 examines the reliability and over testing of RTBs.
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f fl 9608010270 960717 PDR ADOCK 0500o382 P
Technical Specification Change Request NPF-38-174 W3F1-96-0004 Page 2 July 17,1996 This proposed change is being submitted as part of the Cost Beneficial Licensing Action (CBLA) program established within NRR where increased priority is granted to licensee requests for changes requiring staff review that involve high cost without a commensurate safety benefit. The proposed change is expected to realize safety benefits and a cost savings of about $430,000 over the life of the plant.
The proposed change has been evaluated in accordance with 10CFR50.91(a)(1) using criteria in 10CFR50.92(c) and it has been determined that the proposed change involves no significant hazards considerations. The Plant Operations Review and Safety Review Committees have reviewed and accepted the proposed change based on the evaluation mentioned above.
Should you have any questions or comments concerning this request, please contact Paul Caropino at (504)739-6692.
Very truly yours,
/3 M.B. Sellman Vice President, Operations Waterford 3 MBS/PLC/ssf
Attachment:
Affidavit NPF-38-174 cc:
L.J. Callan, NRC Region IV C.P. Patel, NRC-NRR R.B. McGehee N.S. Reynolds NRC Resident inspectors Office Administrator Radiation Protection Division 1
(State of Louisiana)
R American Nuclear insurers
l UNITED STATES OF AMERICA l
NUCLEAR REGULATORY COMMISSION l
l In the matter of
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l Entergy Operations, Incorporated
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Docket No. 50-382 Waterford 3 Steam Electric Station
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i AFFIDAVIT M.B. Sellman, being duly sworn, hereby deposes and says that he is Vice President, Operations - Waterford 3 of Entergy Operations, incorporated; that he is duly authorized to sign and file with the Nuclear Regulatory Commission the attached Technical Specification Change Request NPF-38-174; that he is familiar with the content thereof; and that the matters set forth therein are true and correct to the best of his knowledge, information and belief.
s M.B. Sellman Vice President, Operations - Waterford 3 STATE OF LOUISIANA
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) ss PARISH OF ST. CHARLES
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Subscribed and sworn to before me, a Notary Public in and for the Parish and State above named this 17 F" day of d vuY 1996.
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Notary Public My Commission expires e"
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i DESCRIPTION AND SAFETY ANALYSIS OF PROPOSED CHANGE NPF-38-174
- This proposed change extends the surveillance interval for the Reactor Trip Breakers (RTBs) from monthly to quarterly and increases the allowed outage time for operation with an inoperable RTB from 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />.
Existina Specification See Attachment A Proposed Specification See Attachment B Backaround During the early eighties, every type of switchgear used for automatic tripping in the reactor protection systems of Pressurized Water Reactor (PWR) plants experienced anomalies associated with the under voltage trip function. The problems surfaced at Salem Nuclear Plant with an Anticipated Transient Without Scram (ATWS). This led to industry-wide investigations into causes of RTB failures. For the GE breakers, the problems were attributed to poor maintenance practices, hardening of trip latch bearing
. lubricant and inadequate attention to detail in dimensional checks for Under Voltage trip device.
The ATWS event culminated with the NRC and industry imposing requirements (e.g.,
Generic Letter 83-28, " Required Actions Based on Generic Implications of Salem ATWS Event") that included extensive testing of RTBs, performance trending, meticulous preventive maintenance guidelines and replacement of bearing lubricant.
Plant designs were also changed (10 CFR 50.62) to provide diverse tripping for the reactor in case of ATWS.
As part of the Technical Specification Improvement Program, the NRC Staff reviewed the basis for technical specification test frequencies to ensure that the tests promote safety and do not degrade equipment. The staffs review results were presented in NUREG-1366, " Improvements to Technical Specification Surveillance Requirements,"
which found that while some testing at power is essential to verify equipment and system operability, safety can be improved, equipment degradation decreased, and unnecessary personnel burden relaxed by reducing the amount of testing at power.
Section 5.5 of NUREG-1366 discusses the staffs findings associated with Reactor Trip Breaker Testing at PWRs and recommends that the vendor owner groups consider whether recent operating experience would justify a change in the test interval for reactor trip and bypass breakers.
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'l In agreement with the staff's recommendation the Combustion Engineering Owners Group sponsored the preparation of CE NPSD-951, Reactor Trip Circuit Breakers i
Surveillance Frequency Extension, to provide this further study.
The CEOG has developed CE NPSD-951 as justification for extending the surveillance interval and allowed outage time for RTBs. This proposed technical specification change constitutes a lead-plant submittal, applicable to 13 plants with Combustion Engineering (CE) designed Nuclear Steam Supply System (NSSS).
Descriotion The proposed change modifies TS Table 4.3-1 item 13, Reactor Trip Breaker channel functional test frequency, by changing the M (monthly) to a Q (quarterly). Table notation (11) was added to Table 4.3-1. This note requires the quarterly channel functional test and the quarterly Reactor Protection System Logic channel functional test to be scheduled and performed such that each Reactor Trip Breaker is tested at least once every 6 weeks. The six week interval is the maximum vendor recommended interval for cycling of each RTB. Items 12 and 13 of Table 4.3-1 are modified to reference note 11. The proposed change also increases the allowed outage time for the Reactor Trip Breakers in Table 3.3-1 Action 5 from 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br />. The Bases is updated to reference CE NPSD-951 and reflect the proposed change.
J All of the transient and accident analyses that call for a reactor trip assume that the reactor trip breakers (RTBs) operate and interrupt power to the control element drive mechanism (CEDMs). The Technical Specifications, therefore, require a functional test of the RTBs monthly during operation, each startup and following maintenance. The functional tests independently test the under voltage and shunt trip devices. The RTBs are also tested as part of the of Reactor Protective instrumentation channel functional tests performed quarterly and every 18 months. These frequent operations of the RTBs are causing excessive wear and tear of the mechanisms and are detrimental for the reliability of the breakers.
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The following indicates the minimum number of times each RTB is tested (per Waterford 3 TS) during each refueling cycle:
18 TS Table 4.3-1 item 13 RTB Monthly Test i
36 TS Table 4.3-1 item 12 RPS Logic Quarterly Test 1
_TS Table 4.3-1 item 1 Manual Reactor Trip l
1 TS Table 4.3-1 item 13 Shunt Trip Device 1
TS Table 4.3-1 item 1 Under Voltage Trip Device 57 Total test required by TS Per Fuel Cycle.
Under the proposed change the number of required tests on each RTB would be reduced from 57 to 45. This reduction in testing is intended to increase the reliability of RTB, while minimizing the potential for challenges to plant systems as a result of inadvertent scrams.
Since the Salem event, extensive experience on the failures of RTBs has been gained.
l The anomalies required corrective action involving adjustments to bring the under l
voltage (UV) device and the switchgear into compliance with manufacturer i
specifications and application of suitable lubricant for trip shaft bearings. Actions completed pursuant to Generic Letter 83-28 section 4.2, " Preventive Maintenance and Surveillance Program for Reactor Trip Breakers" have been effective in improving RTB reliability. The Waterford 3 preventive maintenance program for RTBs received NRC l
staff approval via Safety Evaluation Report, dated October 28,1987. This maintenance program is periodically reviewed to ensure that appropriate recommendations are being followed and the frequency of such maintenance is appropriate.
The types of RTB failures experienced today appear to be related to performance degradation caused by mechanical fatigue or mechanical stress on operating devices due to opening and closing actions. At Waterford 3, the most common failure mode is tearing of the sheet metal housing the front frame assembly. This is attributed to the constant hammering action of the spring carrier mechanism striking the stop pin on every operation. Thus, the more frequent surveillance testing of the breakers is leading to significant replacement of front frame assemblies.
Waterford 3 has installed a diverse scram system in compliance with 10 CFR 50.62 as l
ATWS protection. The system is described in the updated Final Safety Analysis Report l
section 7.8. The modifications associated with 10 CFR 50.62 further reduce the risk resulting from the failure of the RTBs.
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.i Safety Analvsis The proposed change described above shall be deemed to involve a significant hazards consideration if there is a positive finding in any of the following areas:
1.
Will operation of the facility in accordance with this proposed change involve a significant increase in the probability or consequences of any accident previously evaluated?
Response
No The proposed change to increase RTB surveillance interval will have no significant effect on the probability or consequences of any accident previously.
evaluated. As previously stated, all of the transient and accident analyses that i
call for a reactor trip assume that the reactor trip breakers (RTBs) operate and interrupt power to the control element drive mechanism (CEDMs). Extensive testing results, indicate that the RTBs are available and capable of performing their safety-related function. Currently RTBs are verified operable every 4 weeks. Under the proposed change RTBs would be verified operable at least every 6 weeks. This reduced testing frequency is intended to increase component reliability. The increase in the testing interval cannot increase i
component failure rate or the potential for component failure.
The proposed change to increase the allowed outage time for RTBs from i hour to 2 hours2.314815e-5 days <br />5.555556e-4 hours <br />3.306878e-6 weeks <br />7.61e-7 months <br /> will have no significant impact on probability or consequences of any accident previously evaluated. When an RTB is inoperable, Functional Testing and other beaker operations becomes more difficult. The current technical specification allows an inoperable breaker to be closed for 1 hour1.157407e-5 days <br />2.777778e-4 hours <br />1.653439e-6 weeks <br />3.805e-7 months <br /> to perform testing of other RTBs. This provision is infrequently required, but when it is i
required, the allowed outage time is very short and rushing to complete a test may lead to an inadvertent reactor trip. Increasing this allowed outage time is an improvement item identified in NUREG 1366 and consistent with philosophy provided in Generic Letter 89-07.
Therefore, the proposed change will not involve a significant increase in the probability or consequences of any accident previously evaluated.
2.
Will operation of the facility in accordance with this proposed change create the possibility of a new or different type of accident from any accident previously evaluated?
Response
No This proposed change does not involve any changes in equipment and will not alter the manner in which the plant will be operated.
Therefore, the proposed change will not create the possibility of a new or different kind of accident from any accident previously evaluated.
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3.
Will operation of the facility in accordance with this proposed change involve a significant reduction in a margin of safety?
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Response
No i
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The proposed change will not adversely affect the performance of the safety j
function of the RTBs. In fact, it is expected that the performance of the RTBs will i
improve as a result of this change based on less wear and tear on the equipment. The proposed change will have no adverse impact on the protective
.i boundaries, safety limits or margin of safety.
Therefore, the proposed change will not involve a significant reduction in a j
margin of safety.
i Safety and Sianificant Hazards Determination Based on the above safety analysis, it is concluded that: (1) the proposed change j
does not constitute a significant hazards consideration as defined by 10CFR50.92; and (2) there is a reasonable assurance that the health and safety of the public will not be
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endangered by the proposed change; and (3) this action will not result in a condition which significantly alters the impact of the station on the environment as described in j
the NRC final environmental statement.
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